package person.bing.fbcloud.leetcode;

/**
 * @author: mengfanbing
 * @date: 2020/7/15 10:15
 */
public class Q96 {
    public static void main(String[] args) {
        int i = numTrees(4);
        System.out.println(i);
    }
    public static int numTrees(int n) {
        int ans = 1;
        for(int i=0;i<n;i++){
            ans =  ans * 2 * (2 * i + 1) / (i + 2);
        }
        return ans;
    }
}
